Contact arrangement



Nov. 29, 1966 u. TUCHEL CONTACT ARRANGEMENT 2 Sheets-Sheet 1 Filed April29, 1964 INVENTOR Ulrich Tuchel ATTOR NEYS NOV. 29, 1966 u TUCHEL3,289,146

CONTACT ARRANGEMENT Filed April 29, 1964 2 Sheets-Sheet 2 INVENTORUirich Tuchel ATTORNEYS United States Patent 1s Claims. a. 339-176) Thepresent invention relates to a resilient electric contact arrangementwhich is provided with springs which serve to receive and make contactwith a male connector or plug, these springs being so bent as to formtwo or more pairs of contact-making points which pairs are arranged onebehind the other in the direction in which the plug is inserted, andthat these pairs of contact-making points, in rest position of thesprings, are in contact with each other, or nearly so.

It is the primary object of the present invention so to fashion thecontact spring means that the contact pressure which is exerted on theplug by the actual contact-making portion is lower in the first stageand higher in the second, i.e., the contact-making portions which firstphysically engage and electrically contact the plug as the same isinserted exert less pressure than do the contact-making portions whichengage the plug as the same is inserted more deeply into the contactarrangement which serves, in effect, as a socket. As a result, the plugcan first be introduced gently into the spring socket, whereas after theplug has reached the second stage, a greater force is exerted thereon,thereby guaranteeing a reliable contact which will remain constant atall times. Consequently, the surfaces of the plug are protected orconserved while the plug is in the process of being inserted, which isof particular importance in the case of very thin layer-type contactsurfaces, e.g., printed circuits.

Various attempts have been made to solve the above problem, andpreviously proposed contact arrangements incorporate variously curvedand bent springs. None, however, has so far proven satisfactory.According to the present invention, however, the problem is solved byproviding a contact arrangement having two springs for receiving a plug,which springs are bent to form two pairs of contact-making portionswhich pairs are arranged one behind the other in the direction in whichthe plug is to be inserted. The contact'making portions of each pair, inrest position of the springs when no plug is in contact therewith, arein contact with each other, or almost so. That arm of each spring whichextends from the first contact-making portion to a first support pointwhich takes up the inserting pressure and which, already in restposition of the springs, is constituted by a wall of a housing in whichthe springs are located, is softer, i.e., more yieldable, preferably bybeing longer, than that arm of the spring which extends from the secondcontact-making portion to a second point which takes up the insertingpressure and which, already in rest position of the spring, isconstituted by a portion of the first-mentioned arm of the spring whichextends between the second-mentioned arm and the wall of the housing.The second arm has exerted on it, by the mentioned portion of the firstarm, a progressively increasing supporting pressure during thetransition of the spring from rest position to stressed position inwhich the springs receive the plug.

According to one embodiment of the present invention, each spring has anend attached to the housing, and each first arm which engages the innersurface of the housing at the first support point extends from theattached end in a direction opposite to that in which the plug is to beinserted. The spring includes a section which is a continuation of thefirst arm and which is bent back to extend in the direction in which theplug is to be inserted. The

3,289,146 Patented Nov. 29, 1966 section includes the second arm as wellas: the two contactmaking portions of the respective spring and hasintermediate these last-mentioned two contact-making portions a bendwhich is looped convexly toward the first arm. The bend is in contactwith the first arm, with the point of engagement therebetweenconstituting the second support point.

Additional objects and advantages of the present invention will becomeapparent upon consideration of the following description when taken inconjunction with the accompanying drawings in which:

FIGURE 1 is a sectional view showing a contact arrangement according tothe present invention in its rest position, i.e., the position which theparts occupy when no plug has as yet been inserted.

FIGURE 2 is a sectional view showing the position of the parts after theplug has been partly inserted, namely, when the plug has been insertedinto what is hereinafter termed the first stage.

FIGURE 3 is a sectional view showing the position of the parts after theplug has been fully inserted, namely, when the plug has been inserted tooccupy what is hereinafter termed the second stage.

FIGURE 4 is a side view showing the double spring by itself, i.e.,outside of the housing and in its wholly unstressed condition.

FIGURE 5 is a plan view of the double spring shown in FIGURE 4.

FIGURE 6 is a development of the double spring shown inside the housingin FIGURES 1 through 3 and by itself in FIGURES 4 and 5, i.e., FIGURE 6shows the double spring in flat form.

FIGURES 7, 8 and 9 show further embodiments of the present invention.

Referring now to the drawings and first to FIGURE 1 thereof inparticular, the same shows a symmetrical spring, indicated generally atS, arranged within a generally blockshaped housing 6. The region atwhich contact is first established when a plug, such as is indicated atP, is inserted into the contact arrangement in the direction of arrow 7,is indicated at 1. The configuration which the spring assurries, in therest position depicted by FIGURE 1, is fixed, i.e., determined by theinternal configuration of the housing 6. Thus, the spring will be seento touch the inner surface of the housing 6 at each of two points 2,these points, too, being determined by the rest position of the spring Sand the internal configuration of the housing 6. The points 2 are thosepoints of the housing 6 which take up the pressure when the plug isfirst inserted and the two contact-making portions 1 press against theplug P. The second region at which the spring S makes contact with theplug is indicated at 3, and the bearing or supporting points pertainingto this region and taking up the pressure when the plug is insertedfurther, i.e., advanced into its second stage, are indicated at 4.

The symmetrical spring S, being, in effect, a double spring, is soconfigured that, when it occupies its rest position in the housing 6,whose internal configuration is likewise configured and dimensioned tobe generally rectangular, the points 2 lie firmly against the innersurface of the concavity provided at the interior of the housing and theend portions 5 of the two spring halves are firmly anchored at thebottom of the housing, i.e., the end of the housing which is opposite tothe end of the housing through which the plug is inserted. This alreadyassures that the spring S is reliably centered within the housing 6.Also assured is that a very long stretch or length of spring isavailable for pressing the spring against the plug while the latter isin its first stage, namely, a portion extending from the initial pointof contact 1 to the point 2. Consequently, when the plug P is insertedin the direction of the arrow 7, the spring S will yield readily orsoftly as the plug first makes contact with the spring. This is shown inFIGURE 2.

The arrangement of the spring S in the housing 6 also assures that thetwo contact points 3 at which the plug, as the same is advanced from itsfirst to its second stage, next engages the spring, will prior to suchsecond engagement, contact each other under an initial stress. Thisinitial stress or bias is obtained by a looping bend with which the freeend section 9 of each half of the spring S is provided. Each section 9is bent back at 14 and extends in the direction in which the plug isinserted. These bends 10 bear, under stress, against a portion of arm 3of the corresponding spring half which lies against the inner surface ofthe housing and engages the same at point 2. Each arm 8 is, at thatportion of its length at which it is engaged by the looping bend 10,curved convexly toward the free end section 9. Each section 9 will beseen to include, within its own length, the two contact-making portions1 and 3 and, consequently, the arm extending from the secondcontact-making portion 3 to the second support point 4.

When the plug P is next pushed in further to its second stage, shown inFIGURE 3, the two free end sections 9 are spread apart, so that theinitial stress of those arms of the end portions which extend from thecontact-making point 3 to the bend 10 is progressviely increased. As aresult, the plug P is ultimately clamped very tightly by the spring S,at the points 3. Furthermore, the short length or stretch of each springhalf between points 3 and 4-, as Well :as the reinforcement flanges 12with which each spring half is provided in the region of point 3',brings about an increased stiffening of the free end of the springwhich, in the same manner as the progressively increasing stress, leadsto a firm clamping of the plug by the spring S at the points 3. As shownin FIGURES 1 to 3, the second pair of contact-making portions 3 is atleast approximately at the same level, as seen in the direction in whichthe plug is inserted, as the first support points 2 at which the springsengage the inner surface of the housing 6.

The spring halves are also provided with upstanding flanges 11, 11located in the region of the points 1. These reinforcements, however, donot decrease the resiliency or yieldability of the spring when the plugP is first introduced because the long stretch of spring, extending frombend 14 at the top of each spring half (as viewed in FIG- URES 1 to 3)to the point 2, is available to take up the pressure exerted by the plugP being introduced.

Thus, it is a salient feature of the present invention that that arm ofthe spring S which extends between the first contact-making portion 1and the first support point 2 is softer i.e., yields more readily, thanthat arm of the spring S which extends between the second contact-makingportion 3 and the second support point 4. This greater softness is mostreadily obtained by making the firstmentioned arm longer than thesecond-mentioned arm.

The spring S is additionally secured to the housing 6 by means offlanges 13 and 13.

As is best seen from FIGURES 4 through 6, the entire double spring,including the locking flanges 13 and 13' and the flanges 11, 11', and12, 12, consists of a single leaf spring which has been stamped orpunched to have the requisite configuration. The spring surfaces extend,preferably throughout the entire piece, at right angle to the directionof the elastic pressure forces. The projecting flanges 11, 11' and 12,12', are provided at the two ends of the leaf spring strips. As aresult, there are a plurality of points of actual contact between theplug and the spring which, whenever the plug is inserted or withdrawn,clean themselves and which maintain reliable contact because, should theplug tilt or cant, the spring will twist to adjust itself and establishfirm contact with the twisted plug. This is of special significance, ifas stated above, the plug is constituted by a flat blade.

It will be understood that the above description of the presentinvention is susceptible to various modifications,

changes, and adaptations, and the same are intended to be comprehendedwithin the meaning and range of equivalents of the appended claims. Forexample, the spring can be configured to provide more than twocontactmaking regions. Furthermore, the spring S need not be doublespring, in that but one-half of the full spring shown in the drawingscan be used to establish reliable contact with a plug, as shown inFIGURE 7. On the other hand, the spring can be provided with more thantwo opposite symmetrical spring halves, for example, there can be threeor four crossed, preferably non-symmetrical angularly displaced springhalves. One such arrangement is shown in FIGURE 8 in which there are twosets of opposite spring pairs S S and S S each of which makes contactwith the plug P, so that there will be a total of eight contactmakingportions. In the illustrated embodiment, springs S and S areelectrically connected to each other so as to form, in effect, adouble-layered spring, while the springs S and 5. have an insulatinglayer 20 between them so that these two springs ooact to form-a switchwhen the plug is inserted. In the embodiment of FIG- URE 9, the carrierfor the contact cooperating with the spring is not rectilinear butradial, thereby to absorb and to bring about rotary movement of the twocoacting contacts. In FIGURE 9, the straight double arrow shows that theradial carrier body can be moved with respect to the spring. Actually,FIGURE 9 does not illustrate the rest position of the spring, which willbe attained when the carrier body is moved rightwardly even furtheruntil the bend between the two contactmaking portions of the springengages the arm of the spring which itself touches the interior of thehousing 6, thereby to establish a second support point comparable topoint 4 described above.

It will be appreciated that a spring incorporated in a contactarrangement according to the present invention not only provides veryreliable contact but also is susceptible to very economicmass-production techniques. As is best seen from FIGURE 6, the doublespring can be made from a symmetrical stamped blank, which need simplybe folded about its axis of symmetryshown in dashed lines-and then bebent into its final configuration. When the spring is then inserted intothe housing, which, in practice, may be made of plastic, it willautomatically be given its pre-stressed condition. The assembly of thecontact arrangement, i.e., the insertion of the spring into the housing,can easily be accomplished either by machine or by unskilled labor.

What is claimed is:

1. An electric contact arrangement for receiving a plug, said contactarrangement comprising a housing and two springs arranged in saidhousing, said springs being bent to form first and second pairs ofcontact-making portions which pairs are arranged one behind the other inthe direction in which the plug is to be inserted, the contactmakingportions of each pair being, in rest position of said springs when noplug is in contact therewith, at least nearly in contact with eachother, each spring having a first arm which extends from the firstcontact-making portion of the respective spring to a first support pointat which the respective spring, already in its rest position, engages aninterior surface of said housing at which point said housing takes upthe inserting pressure as the plug is inserted, each spring furtherhaving a second arm which extends from said second contact-makingportion of the respective spring to a second support point at which therespective spring, already in its rest position, engages a portion ofthe first arm of the respective spring which arm portion extends betweensaid second arm and said interior surface of said housing, said firstarm being longer than said second arm, and said portion of said firstarm exerting on said second arm a progressively increasing pressureduring the transition of each spring from rest position to a stressedposition in which said springs contact the plug.

2. A contact arrangement as. defined in claim 1 Wherein said second pairof contact-making portions is at least approximately at the same level,as seen in the direction in which the plug is inserted, as said firstsupport points at which said springs engage said housing.

3. A contact arrangement as defined in claim 1 wherein said springs areidentical and are configured symmetrically relative to each other.

4. A contact arrangement as defined in claim 1 wherein said springs areconstituted by leaf springs whose surfaces are at right angles to thedirection of the elastic pressure forces.

5. A contact arrangement as defined in claim 4 wherein said leaf springsurfaces are at right angles to the direction of the elastic pressureforces throughout the entire lengths of the leaf springs.

6. A contact arrangement as defined in claim 1 wherein said two springsare made of a single punched leaf spring, said springs being symmetricalwith respect to each other and being folded about an axis of symmetry ofsaid single punched leaf spring.

7. A contact arrangement as defined in claim 1 comprising a plurality ofsets of springs each set including two springs.

8. A contact arrangement as defined in claim 7 wherein the springs ofeach set are symmetrical with respect to each other.

9. A contact arrangement as defined in claim 1 wherein each spring hasan end attached to said housing, and wherein said first arm whichengages said inner surface of said housing at said first support pointextends from said attached end in a direction opposite to that in whichthe plug is to be inserted, said spring including a section which is acontinuation of said first arm and which is bent back to extend in thedirection in which the plug is to be inserted, said section includingsaid second arm as well as the two contact-making portions of therespective spring and having intermediate said last-mentioned twocontact-making portions a bend which is looped convexly toward saidfirst arm, said bend being in contact with said first arm, the point ofengagement between said bend and said first arm constituting said secondsupport point.

10. A contact arrangement as defined in claim 9 wherein said first armis convexly looped toward said section.

11. A contact arrangement as defined in claim 9 wherein each attachedend extends through said housing at that end of said housing which isopposite to the end thereof through which the plug is inserted.

12. A contact arrangement as defined in claim 9 wherein said section isprovided with projections at at least one of said contact-makingportions.

13. A contact arrangement as defined in claim 12 wherein said spring isconstituted by a single stamped leaf spring and wherein said projectionsare flanged at right angles to the spring surface,

14. A contact arrangement as defined in claim 13 wherein saidprojections are provided at each edge of the leaf spring.

15. A contact arrangement as defined in claim 13 wherein said springfurther comprises integral attaching flanges extending in oppositedirections.

16. A contact arrangement as defined in claim 7 wherein one spring ofone set is superimposed on one spring of another set, said twosuperimposed springs being electrically connected to form, together, adouble-layered spring.

17. A contact arrangement as defined in claim 7 wherein one spring ofone set is superimposed on one spring of another set, there being alayer of insulation between said superimposed springs.

18. An electric contact arrangement having two springs for contacting aplug, each of said springs being constituted by a single stamped leafspring, said springs being bent to form two pairs of contact-makingportions which pairs are arranged one behind the other in the directionin which the plug is to be inserted, the contactmaking portions beingprovided with flanges projecting at right angles to the spring surface,the contact-making portions of each pair, in rest position of saidsprings when no plug is in contact therewith, being at least nearly incontact with each other, that arm of each spring which extends from thefirst contact-making portion to a first support point which takes up theinserting pressure and which, already in rest position of the springs,is constituted by a wall of a housing in which said springs are located,being softer than that arm of the spring which extends from the secondcontact-making portion to a second point which takes up the insertingpressure and which, already in rest position, is constituted by aportion of the first-mentioned arm of said spring which extends betweenthe second-mentioned arm and the wall of the housing, said second armhaving exerted on it, by said portion of said first arm, a progressivelyincreasing supporting pressure during the transition of the spring fromrest position to stressed position in which said springs contact theplug.

References Cited by the Examiner UNITED STATES PATENTS 1,798,375 3/1931Greenwood 339-258 X 2,539,230 1/1951 Craig 339-258 X 2,908,775 10/1959Gilbert 339-17 X 3,015,083 12/ 1961 Juris 339-17 3,149,899 9/1964Johanson 339-176 X 3,160,459 12/1964 Greco et a1. 339-258 X 3,218,60311/1965 Sanislo 339-176 EDWARD C. ALLEN, Primary Examiner.

W. DONALD MILLER, Examiner,

1. AN ELECTRIC CONTACT ARRANGEMENT FOR RECEIVING A PLUG, SAID CONTACTARRANGEMENT COMPRISING A HOUSING AND TWO SPRINGS ARRANGED IN SAIDHOUSING, SAID SPRINGS BEING BENT TO FORM FIRST AND SECOND PAIRS OFCONTACT-MAKING PORTIONS WHICH PAIRS ARE ARRANGED ONE BEHIND THE OTHER INTHE DIRECTION IN WHICH THE PLUG IS TO BE INSERTED, THE CONTACTMAKINGPORTIONS OF EACH PAIR BEING, IN REST POSITION OF SAID SPRINGS WHEN NOPLUG IS IN CONTACT THEREWITH, AT LEAST NEARLY IN CONTACT WITH EACHOTHER, EACH SPRING HAVING A FIRST ARM WHICH EXTENDS FROM THE FIRSTCONTACT-MAKING PORTION OF THE RESPECTIVE SPRING TO THE FIRST SUPPORTPOINT AT WHICH THE RESPECTIVE SPRING, ALREADY IN ITS REST POSITION,ENGAGES AN INTERIOR SURFACE OF SAID HOUSING AT WHICH POINT SAID HOUSINGTAKES UP THE INSERTING PRESSURE AS THE PLUG IS INSERTED, EACH SPRINGFUTHER HAVING A SECOND ARM WHICH EXTENDS FROM SAID SECOND CONTACT-MAKINGPORTION OF THE RESPECTIVE SPRING TO A SECOND SUPPORT POINT AT WHICH THERESPECTIVE SPRING, ALREADY IN ITS REST POSITION, ENGAGES A PORTION OFTHE FIRST ARM OF THE RESPECTIVE SPRING WHICH ARM PORTION EXTENDS BETWEENSAID SECOND ARM AND SAID INTERIOR SURFACE OF SAID HOUSING, SAID FIRSTARM BEING LONGER THAN SAID SECOND ARM, AND SAID PORTION OF SAID FIRSTARM EXERTING ON SAID SECOND ARM A PROGRESSIVELY INCREASING PRESSUREDURING THE TRANSISTION OF EACH SPRING FROM REST POSITION TO A STRESSEDPOSITION IN WHICH SAID SPRINGS CONTACT THE PLUG.